logbd64.3m (2010 09)

l
logbd64(3M) logbd64(3M)
(HP Integrity Server Only)
NAME
logbd64(), logbd128(), logbd32() - decimal exponent functions
SYNOPSIS
#define __STDC_WANT_DEC_FP__
#include <math.h>
_Decimal64 logbd64(_Decimal64 x);
_Decimal128 logbd128(_Decimal128 x);
_Decimal32 logbd32(_Decimal32 x);
DESCRIPTION
The logbd64() function computes the exponent of the floating point value x. Formally, the return
value is the integral part of log base 10 of |x| as a signed floating point value, for nonzero x.
If x is subnormal, it is treated as though it were normalized, before the exponent is determined.
logbd128() is a _Decimal128 version of logbd64(); it takes a
_Decimal128 argument and
returns a
_Decimal128 result.
logbd32() is a _Decimal32 version of logbd64(); it takes a _Decimal32 argument and returns a
_Decimal32 result.
These math functions are supported for HP-UX 11i Version 3 September 2008 Update and forward.
USAGE
To use any of these functions, compile with the +decfp option.
Make sure your program defines
__STDC_WANT_DEC_FP__
and then includes <math.h>.
Link in the math library by specifying
-lm or -l:libm.a on the linking command line.
For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site:
http://www.hp.com/go/fp
.
RETURN VALUE
If x is ±infinity,
logbd64() returns +infinity.
If x is 0,
logbd64() returns −infinity and raises the divide-by-zero floating-point exception.
If x is NaN,
logbd64() returns NaN.
ERRORS
If x is 0,
logbd64() sets errno to [ERANGE].
SEE ALSO
frexpd64(3M), ilogbd64(3M), scalbnd64(3M), scalblnd64(3M), math(5).
STANDARDS CONFORMANCE
These functions conform to ISO/IEC TR 24732, "Extension for the programming language C to support
decimal floating-point arithmetic".
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1